Module 3 Biology

When the net movement of water in and out a cell is zero, that solution is said to be

isotonic.

The cis face of the Golgi complex is most directly involved in which process?

Accepting vesicles from the ER

When food is scarce, the amoeba-like cellular slime mold, Dictyostelium, secretes which compound?

Cyclic adenosine monophosphate

Where are calcium ions stored before a signaling pathway releases them into the cytosol?

Endoplasmic reticulum

Which cellular mechanism ejects products, such as hormones, by the fusion of a vesicle with the plasma membrane?

Exocytosis

Sodium ions enter the cell.

Ion channel-linked receptor

What can happen when GABA binds to its receptor?

Neural signaling is inhibited.

What transmits information electrically and chemically?

Neurons

Which statement about plasma membranes is false?

Plasma membranes prevent communication with other cells.

Mutations to ABC transporter genes contribute to cystic fibrosis.

True

The gas ethylene is a plant hormone that regulates a variety of processes, including seed germination and ripening of fruit.

True

Which is a major group of enzyme-linked receptors?

Tyrosine kinases

Typically, the gate of an ion channel remains closed until a(n) ____ binds to the receptor.

ligand

In the sodium-potassium pump, sodium ion release causes the carrier protein to return to its original shape and releases two K+ ions into the cell.

False

Plasmolysis occurs in plant cells when the soil or water contains low concentrations of salts or fertilizers.

False

When food is abundant, the cellular slime mold Dictyostelium secretes cAMP into the environment to signal the formation of a multicellular slug-shaped colony.

False

The following are different types of neurotransmitters EXCEPT

cyclic adenosine.

During enzyme-linked reception, signal molecules bind to two tyrosine kinase receptors. The receptor proteins move closer together in the plasma membrane and pair, forming a(n) ____.

dimer

In a lipid bilayer, __________ fatty acid tails face each other within the bilayer and form a region that excludes water.

hydrophobic

Evidence that all living cells have a common origin is best illustrated by:

the basic similarities in cell structure and chemistry

The smooth ER is the primary site for the synthesis of proteins and cholesterol needed to make membranes.

False

When a signaling molecule binds to a G protein-linked receptor, the ligand-receptor complex associates with GDP protein and causes GDP to be replaced by GTP.

False

When an enzyme-linked receptor is activated, a conformational change activates the extracellular kinases.

False

In the cAMP signal transduction pathway, a protein kinase is activated. What happens next?

The protein kinase activates a cellular response.

What is a characteristic found in both prokaryotic and eukaryotic cells?

plasma membrane

Choanoflagellates are important in the study of cell communication evolution because choanoflagellates have

protein kinases similar to those in animals.

What is calmodulin?

A calcium-binding protein

How do gap junctions differ from desmosomes?

A gap junction provides communication between cells.

What type of cellular junction cements cells together that use cadherins as a belt around each cell?

Adhering junctions

Name the part of the cell outside the nucleus.

Cytoplasm

Protein kinase sites are active.

Enzyme-linked receptor

Biological membranes are one-dimensional fluids.

False

Peroxisomes are found in large numbers in cells that synthesize, store, and degrade lipids, and one of their functions is to break down protein molecules.

False

DAG is the second messenger.

G protein-linked receptor

GDP is replaced with GTP.

G protein-linked receptor

Why can cholesterol act as a "fluidity buffer" in cell membranes?

It is slightly amphipathic because of the presence of one hydroxyl group.

A receptor on the cell surface usually has several domains. What is the function of the external domain?

It is the docking site for a signaling molecule.

Which statement about G protein is false?

One subunit binds ATP.

Which is a part of a signal transduction pathway that enables vision in dim light in vertebrates?

Rhodopsin

Microfilaments are linked with one another and with other proteins by linker proteins.

True

What are the colors of an electron micrograph?

black and white

Peripheral proteins are linked to either surface of the plasma membrane by

bonding to integral proteins through noncovalent interactions.

Phosphodiesterase catalyzes the conversion of

cAMP to AMP.

In many cells, including almost all animal cells, the centrosome contains two structures called _________.

centrioles

Which cellular structure is correctly matched to the role it plays within the cell?

centrosome−cell division

What type of microscopy uses a laser to excite fluorophores in a thin "slice" through a cell?

confocal microscopy

The sodium-potassium pump is a carrier protein that maintains a(n) ____ gradient across the plasma membrane.

electrochemical

Phosphate comes from ATP.

enzyme-linked receptor

Plasmodesmata of plant cells are functionally equivalent to the ____ of animal cells.

gap junctions

What protects a cell and may help keep other cells at a distance?

glycocalyx

If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be

hypertonic.

A transmembrane protein differs from other membrane proteins because

it completely extends through the membrane.

The ratio of the size of the image seen with the microscope to the actual size of the object is called:

magnification

Which of the following organelles plays an important role in apoptosis, or programmed cell death?

mitochondria

The process by which the plasma membrane separates from the cell wall is called ______.

plasmolysis

If the cells are physically close to one another, a signaling molecule on one cell may combine with a _________ on another cell.

receptor

What facilitates the rapid transport of water through the plasma membrane?

Aquaporins

Which statement about Ras proteins is false?

They are inactivated when phosphorylated.

Adenylyl cyclase catalyzes the reaction in which

ATP is converted to cAMP.

What have studies of glucose transport in liposomes revealed?

The binding of glucose triggers a conformational change in the carrier protein.

What is the microtubule arrangement of a flagellum or cilium?

9 + 2 arrangement

The peripheral membrane proteins can be easily removed without disrupting the bilayer structure of the membrane.

True

What is generally the maximum magnifying capacity of a light microscope?

2000

What is required for facilitated diffusion to take place?

A transmembrane protein

In the IP3 pathway, what is the function of IP3?

Binds calcium channels in the ER

Which is an example of a second messenger?

Cyclic AMP

Where are hormones produced in animals?

Endocrine glands

In scanning electron microscopy, an electron beam passes through a very thin slice of a specimen and then falls onto a photographic plate or a fluorescent screen. True

False

What type of protein can transduce a signal in two directions?

Integrins

What is the passive movement of water along a concentration gradient?

Osmosis

Which proteins are located on the inner or outer surface of the plasma membrane, usually bound to exposed regions of integral proteins by noncovalent interactions?

Peripheral membrane proteins

In cells that are constantly involved in secretion, an equivalent amount of membrane must be returned to the interior of the cell for each vesicle that fuses with the plasma membrane; if this does not occur, then what would happen?

The cell surface will keep expanding.

How do the phospholipids in vegetable oil differ from those of animal fat?

The fatty acid tails bend.

How is paracrine signaling different from other types of signaling?

The signaling molecules are diffused through interstitial fluid and act on nearby cells.

Most intracellular receptors are what type of protein?

Transcription factors

Almost every vertebrate cell has a primary cilium, a single cilium on the cell surface that serves as a cellular antenna.

True

Cells that secrete large amounts of glycoprotein have many Golgi stacks.

True

In animal cells, the main microtubule organizing center (or centrosome) is important in cell division.

True

Most plasmodesmata contain a narrow cylindrical structure, called the desmotubule, which runs through the channel and connects the smooth ER of the two adjacent cells.

True

Which strategy is the most effective for larger cells to have an effective surface area to volume ratio?

having thin, finger-like projections

Sodium-potassium pumps help to maintain a separation of charges across the plasma membrane, which is called the _________________.

membrane potential

You isolate a cellular structure and determine that it is composed of α-tubulin and β-tubulin. Based on this evidence, you correctly identify this structure as a(n):

microtubule

Which two organelles are responsible for converting energy into forms that can be used by cells?

mitochondria and chloroplasts

Which of the following serves as a framework for the orderly distribution of chromosomes during cell division?

mitotic spindle

The outer part of a G protein-linked receptor binds to a(n) ____, and its inner part binds to a(n) ____.

signaling molecule; G protein

What is the primary function of mitochondria?

transformation of energy

Carrier proteins are also called ______.

transporters

Upon observing a cell of a grass blade, you notice a prominent sac that occupies a large portion of the cell. Which organelle is this?

vacuole